learn.howToCalculate
learn.whatIsHeading
QTc normalises the QT interval for heart rate. Prolonged QTc (>450ms men, >470ms women) signals risk of torsades de pointes, a potentially fatal arrhythmia.
Công thức
QTc (Bazett) = QT (ms) / √RR (seconds); QTc (Fridericia) = QT / ∛RR; Normal < 450 ms (men), < 460 ms (women)
- QT
- QT interval duration (Milliseconds)
- RR
- RR interval (heart rate) (Seconds)
- QTc
- Corrected QT interval (Milliseconds)
Hướng dẫn từng bước
- 1Bazett: QTc = QT / √RR (RR in seconds)
- 2Fridericia: QTc = QT / RR^(1/3) — more accurate
- 3RR (sec) = 60 / HR (bpm)
- 4Critical: QTc > 500ms requires urgent review
Ví dụ có lời giải
đầu vào
QT = 380ms, HR = 60 bpm (RR = 1.0s)
Kết quả
QTc (Bazett) = 380ms — Normal
Câu hỏi thường gặp
Why correct QT for heart rate?
QT interval shortens with faster heart rate. Raw QT depends on HR. Correction isolates intrinsic QT duration. Allows comparison across patients/time.
What does prolonged QTc mean?
Risk factor for torsades de pointes (dangerous arrhythmia). Causes: medications (antipsychotics, antibiotics, antiemetics), electrolyte abnormalities (K, Ca, Mg), congenital (Long QT syndrome).
When should I check QTc?
Baseline ECG before starting QT-prolonging medications. Repeat if adding second drug, or symptoms (syncope, palpitations). Monitor electrolytes (K, Mg critical).
Sẵn sàng để tính toán? Dùng thử Máy tính Corrected QT miễn phí
Hãy tự mình thử →